1. Field of the Invention
The present invention relates to a furnace for melting a metal, such as aluminium and holding the melted metal, and more precisely it relates to a continuous melting and holding furnace.
2. Description of the Related Art
There is a known metal melting furnace which melts a metal and holds the melted metal in a holding chamber, so that the melted metal held in the holding chamber can be ladled out from a ladling chamber into a mold, as disclosed, for example in Japanses Examined Patent Publication No. 62-23234 which was filed in the name of the assignee of the present application. In the known furnace as mentioned above, it is very difficult to control the quality of the melted metal which is ladled from the ladling chamber into the mold.
Namely, first, it is necessary to effectively remove hydrogen gas contained in the melted metal therefrom. Second, it is very important to control the temperature of the melted metal ladled from the ladling chamber. In other words, it is significant to prevent a reduction of temperature of the melted metal. These requirements are important not only from the viewpoint of quality control but also from the viewpoint of effective utilization of energy.
To remove hydrogen or other undesirable gas, it is known to provide in the ladling chamber a bubbling device which ejects an inert gas into the melted metal. However, a space for providing the bubbling device in the ladling chamber is restricted, and accordingly no effective ventilation (gas removal) effect can be expected.
There is a temperature difference of about 100.degree. C. of the melted metal between the ladling chamber and the holding chamber. Therefore, in practice, the temperature of the melted metal in the holding chamber is controlled to be higher by 100.degree. C. than that in the ladling chamber. This however results in an increased enegy consumption and an increased cost of operation of the furnace.
The primary object of the present invention is therefore to provide a compact continuous metal melting furnace in which the quality control of a melted metal, particularly, the ventilation can be easily effected to control the temperature at a desired value.